In order to power autonomous computers and sensors, for example in the area of the Internet of Things (IoT), batteries as an energy source alone are insufficient for devices deployed in remote locations and/or in use for extended time periods. Thus, energy harvesting is required, and the most ubiquitous source of energy is light. Hence, photovoltaic devices can be integrated with batteries to provide recharging capabilities. While such photovoltaic device/battery couplings exist, the available solutions have notable drawbacks such as the use of expensive and rare or toxic materials or, in the alternative, abundant/non-toxic silicon which is not applicable to thin film photovoltaics.
Ultra-small, ultra-low power computers require power to be supplied at constant voltage. Standard lithium (Li)-ion batteries operate at ˜3-4 volts (V), which is too high for low power computers. Therefore, integrated circuit (IC) voltage regulation is needed which wastes energy. Additionally, non-toxic materials for wide deployment in the environment are a requirement along with a spatially small footprint.
Accordingly, improved photovoltaic device and battery integrated designs would be desirable.